1. Field of the Invention.
The present invention relates generally to pig apparatuses, and more particularly, but not by way of limitation, to an integrally formed pipeline pig apparatus having a plurality of flexible cup members, each of the cup members having a substantially external parabolic configuration.
2. Description of the Prior Art.
Pig apparatuses for passage through a pipeline have long been known and used in the petroleum industry. The pig apparatus is inserted into the pipeline and moved through the pipeline by fluids travelling through the pipeline.
Pipeline pig apparatuses are used for a number of purposes, including scraping the interior walls of a line to remove rust and encrustation, separating one fluid component from another, and when used in pipelines for conveying gas, forcing the removal of water and other liquids which have condensed in the line and settled in low areas.
Generally, pig apparatuses of the prior art include an elongated body member and two or more disc-shaped scraper cup members which are attached to the body member. Each of the scraper cup members is made of a resilient material, and completely fills the inside of the pipeline so that the pressure of the fluid being transported through the pipeline pushes the pig apparatus through the pipeline in the direction of fluid flow.
While the pig apparatuses of the prior art have generally been accepted by the industry, problems have nevertheless been encountered in the use of many of such apparatuses. For example, certain of the prior art pig apparatus do not possess the desired flexibility which results in the apparatus becoming logged in the pipeline when bends and obstacles are encountered; other of the prior art devices may become disassembled in the pipeline; and others, especially those having a tubular body portion, require an increased differential pressure to move the apparatus through the pipeline which results in excessive wear on the scraper cup members due to the increased frictional drag resistance exerted on the scraper cup members as the apparatus is moved through the pipeline.